Bt cotton and the predator Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) in the management of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) resistance to lambda-cyhalothrin

Journal of Pest Science - This study sought to provide relevant information for developing effective programs to manage Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) resistance to...     

Field resistance of Spodoptera litura (Lepidoptera: Noctuidae) to organophosphates, pyrethroids, carbamates and four newer chemistry insecticides in Hunan, China

The present studies were carried out to evaluate resistance in the populations of Spodoptera litura Fab. (Lepidoptera, Noctuidae) from five districts of Hunan Province in China to various insecticides from 2010 to 2012 using a standard leaf dip bioassay method. For organophosphates and pyrethroids, resistance ratios compared with a susceptible Lab-BJ strain were in the range of 14–229-fold for organophosphates and 12–227-fold for pyrethroids. Similarly, relative low levels of resistance to emamectin, indoxacarb, and chlorfenapyr were observed in all five populations. In contrast, the resistance to carbamates (thiodicarb or methomyl) was significantly higher than that of organophosphates, pyrethroids and newer chemistry insecticides. The pairwise correlation coefficients of LC₅₀ values indicated that the newer chemistry insecticides and old generation insecticides were not significant except abamectin, which was negatively significantly correlated with methomyl. A significant correlation was observed between thiodicarb, methomyl, and deltamethrin, whereas resistance to bifenthrin showed no correlations with resistance to other insecticides except deltamethrin. The results are discussed in relation to integrated pest management for S. litura with special reference to management of field evolved resistance to insecticides.     

Potential of the entomopathogenic nematodes Steinernema feltiae , S. weiseri and Heterorhabditis bacteriophora for the biological control of the sugar beet weevil Bothynoderes punctiventris (Coleoptera: Curculionidae)

The sugar beet weevil, Bothynoderes punctiventris Germ. (Coleoptera: Curculionidae), is one of the most damaging pests of sugar beets in Turkey and has been traditionally controlled by application of large amounts of insecticides. The current study used laboratory microcosms to evaluate the possibility of using entomopathogenic nematodes as an alternative control method. The nematodes Steinernema feltiae (strain TUR-S3), Steinernema weiseri (BEY) and Heterorhabditis bacteriophora (TUR-H2) had previously been isolated from Turkey. Nematode-induced mortality generally increased as soil temperature increased from 15 to 25°C but decreased when larvae were located deeper in soil. Heterorhabditis bacteriophora caused the highest larval mortality at 25°C at all depths (5–20 cm). Steinernema feltiae and S. weiseri were more effective than H. bacteriophora at 15°C at all depths. Increasing the application rate of infective nematode dauer juveniles (DJs) affected the number of DJs that penetrated each insect larva and the number of DJs produced per insect. The highest production of DJs per larva occurred at application rates of 50 DJs/larva for S. feltiae and S. weiseri and 100 DJs/larva for H. bacteriophora. Reproduction decreased again at higher application rates. Heterorhabditis bacteriophora had the highest reproductive capability. The results indicate that S. feltiae and S. weiseri might be more effective against this pest early in the growing season when soil temperature is low and that H. bacteriophora might be more effective later in the season when temperature increases.     

Biological impact of harmaline,ricinine and their combined effects with <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> on <Emphasis Type="Italic">Spodoptera exigua</Emphasis> (Lepidoptera: Noctuidae)

The history of botanical pesticides reveals that their study did mainly focus on the determination of acute median lethal dose or concentration. In the current situation, it is the dire need to understand the sublethal effects of the botanical extracts along with the traditional studies of lethal concentrations in order to comprehensively investigate the future role of the botanical extracts as pesticides. This study reveals the effects of traditionally used medicinal plant extracts harmaline (H) and ricinine (R) either individually or in combination with Bacillus thuringiensis (Bt) on the acute toxicity and sublethal effects on the nutrition and enzyme system of Spodoptera exigua. Harmaline and ricinine caused reduction in the growth of neonate larvae up to 93.12 and 84.31%. The EC₅₀ values of harmaline against fourth and fifth instars were 0.24 and 0.27 mg/ml, but these values remained 0.49 and 0.54 mg/ml against fourth and fifth instars after being treated with ricinine. The combination of harmaline and ricinine with Bt resulted in the increased efficiency of these chemicals as the mortality percentages significantly increased up to 96 and 87.82% in significantly less exposure time in case of H + Bt and R + Bt respectively, as compared to individual treatments. The nutritional analysis revealed the increased toxicity of harmaline and ricinine in combination with Bt, but H + Bt2 showed the higher efficiency with minimal relative consumption rate 2.50 mg/mg/day, relative growth rate 1.16 mg/mg/day and efficiency of conversion of ingested food 29.66% of control, respectively. Changes in antioxidant enzymes such as superoxide dismutase (SOD) and catalases (CAT) were noticed to some extent over different exposure times at all the treatments. The highest SOD (+37.29%) and CAT (+29.27%) activity was observed at the 6th day of treatment with H + R + Bt2. The study clearly shows the significantly increased efficiency of harmaline and ricinine in combination with Bt against S. exigua. This phenomenon can be helpful in order to develop better control strategies against different notorious pests.     

Contribution of cultivated crops,vegetables, weeds and ornamental plants in harboring of <Emphasis Type="Italic">Bemisia tabaci </Emphasis>(Homoptera: Aleyrodidae) and associated parasitoids (Hymenoptera: Aphelinidae) in cotton agroecosystem in Pakistan

The population dynamics of Bemisia tabaci and its parasitoids was studied on Gossypium hirsutum, Cucumis melo, Helianthus annus, Glycine max, Solanum melangena, Cucurbita pepo melopopo, Bauhinia pupurea, Morus alba, Albizzia lebbek, Lantana camara, Achyranthus aspera, and Convolvulus arvensis in cotton growing areas of Punjab, Pakistan during 2004 and 2005. Whitefly infested leaves having maximum number of second to third instar were collected and kept in glass petri dishes with lid on at 28 ± 2°C and 65 ± 3% RH. Mean population of whitefly adults that emerged per 200 cm² leaf area per sampling period recorded was maximum on G. hirsutum (43.2), followed by C. melo (31.5), L. camara (23.0), H. annus (20.5), G. max (19.3), C. pepo melopopo (18.1), S. melangena (16.9), A. aspera (11.2), C. arvensis (9.2), B. pupurea (5.4), M. alba (5.3) and A. lebbek (5.0). Percentage parasitism was higher on G. hirsutum (44.3%), followed by C. melo (38.9%), A. aspera (38.3%), L. camara (38.1%), A. lebbek (35.3%), G. max (33.5%), C. arvensis (33.0%), M. alba (31.1%), B. pupurea (27.0%), S. melangena (24.8%), C. pepo melopopo (16.1%) and H. annus (15.2%). Overall the population of whitefly remained low during winter (November–February) and high during summer (May–August) whereas, the percentage parasitism was higher during June–September and lower during December–February. The study revealed that the availability of parasitoids could be enhanced by planting L. camara, B. pupurea, A. lebbek and M. alba in the cotton growing area.